Most semaglutide side effects are gastrointestinal, appear within the first 1–4 weeks, peak during dose increases, and improve as the body adjusts.
Week 1–2 (Starting Semaglutide)
Most common side effects begin here
- Nausea
- Decreased appetite
- Mild stomach pain
- Bloating or gas
- Fatigue
- These effects usually occur within the first few days after the initial dose and are typically mild to moderate.
Week 3–4 (Early Adjustment Phase)
Side effects may continue or slightly increase
- Persistent nausea (often improves with smaller meals)
- Constipation or diarrhea
- Acid reflux or heartburn
- Occasional vomiting
This is when many patients experience the peak of side effects, especially if the dose is increased.
Month 2–3 (Dose Escalation Phase)
Body starts adapting
- GI symptoms gradually decrease
- Appetite suppression stabilizes
- Weight loss becomes more noticeable
Some people may still experience side effects shortly after injections, but they are usually short-lived.
Month 3+ (Maintenance Phase)
Most side effects resolve
- Nausea and GI symptoms are minimal or gone
- Appetite and digestion feel more stable
- Long-term tolerance improves significantly
At this stage, semaglutide is generally well tolerated for most users.
Rare but Serious Side Effects (Can Occur Anytime)
Seek medical attention if you experience:
- Severe abdominal pain (possible pancreatitis)
- Persistent vomiting
- Gallbladder pain (upper right abdomen)
- Signs of low blood sugar (mainly if combined with insulin)
- Thyroid-related symptoms (very rare)
How to Reduce Side Effects
- Start with a low dose and increase gradually
- Eat smaller, high-protein meals
- Avoid fatty or greasy foods
- Stay hydrated
- Take injections on the same day each week
Key takeaway
Semaglutide side effects usually start in the first 1–2 weeks, peak during dose increases, and improve by month 3 as the body adjusts.